fix: repair the configuration cache for NPM tasks by using a mutable instead of an immutable list

workaround for #2372

Author: jGleitz

lib/src/main/java/com/diffplug/spotless/npm/NpmPathResolver.java

@@ -17,6 +17,7 @@
 
 import java.io.File;
 import java.io.Serializable;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
@@ -35,7 +36,9 @@ public NpmPathResolver(File explicitNpmExecutable, File explicitNodeExecutable,
 		this.explicitNpmExecutable = explicitNpmExecutable;
 		this.explicitNodeExecutable = explicitNodeExecutable;
 		this.explicitNpmrcFile = explicitNpmrcFile;
-		this.additionalNpmrcLocations = List.copyOf(additionalNpmrcLocations);
+		// We must not use an immutable list (e.g. List.copyOf) here, because immutable lists cannot be restored
+		// from Gradle’s serialisation. See https://github.com/diffplug/spotless/issues/2372
+		this.additionalNpmrcLocations = new ArrayList<>(additionalNpmrcLocations);
 	}
 
 	/**